Texas Instruments LM13700MX

Overview

LM13700MX from Texas Instruments is a dual operational transconductance amplifier (OTA) with linearizing diodes and high-impedance output buffers, designed for voltage-controlled analog signal processing. It delivers 6-decade gm adjustability (5 μA–500 μA), 0.3 dB gm tracking between channels, ±14.4 V peak buffered output swing, and <0.5 mV input offset voltage - enabling precision stereo audio amplifiers, voltage-controlled filters, and AGC circuits.

For engineers reviewing the LM13700MX datasheet, LM13700MX pinout, LM13700MX application, or LM13700MX equivalent, key selection criteria include transconductance linearity over bias current range, diode-bias-dependent distortion performance, dual-channel matching tolerance, and compatibility with ±15 V or single-supply 9.5–32 V operation in analog synthesis and instrumentation designs.

Technical Context

The LM13700MX implements two independent current-controlled transconductance stages, each with differential NPN input pairs biased by dedicated IABC pins (pins 1/16) and linearizing diodes (pins 2/15) to extend input dynamic range and reduce THD. Its output current is directly proportional to IABC and differential input voltage, with gm ≈ 19.2 × IABC (μS) at 25°C.

Each channel integrates a Darlington-buffered output stage capable of ±20 mA drive and sustained short-to-ground operation, while maintaining buffer input bias current independence from IABC - a key functional distinction from the LM13600 that improves DC stability in audio gain control applications.

Key Specifications

Pinout & Package

LM13700MX is supplied in a 16-pin SOIC package (3.91 mm × 9.90 mm body size) with standard JEDEC MS-012AC footprint and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar operational transconductance amplifier applications.

Compared with LM13600N and NE5517P, the LM13700MX uniquely combines dual matched OTAs, on-die linearizing diodes, and IABC-decoupled buffers - enabling lower-distortion, higher-integration analog signal paths without external compensation components.

Availability

LM13700MX is available at Aetrix Electronics and suitable for stereo audio amplifiers, voltage-controlled filters, automatic gain control circuits, and analog synthesizer modules requiring stable component supply and long-term manufacturability.

Supply support for LM13700MX includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision analog IC design and manufacturing.

The LM13700MX belongs to TI's legacy analog signal processing portfolio, engineered specifically for voltage-controlled analog functions including VCAs, VCFs, VCOs, and programmable impedance networks in professional audio and test equipment.

FAQ

What is the maximum recommended diode bias current (ID) for LM13700MX?

The absolute maximum diode bias current (ID) for LM13700MX is 2 mA per channel, as specified in the Absolute Maximum Ratings table. Operation above this value risks thermal overstress and degraded linearity. For optimal distortion performance, TI recommends 1 mA ID - sufficient to maintain linearizing diode action while minimizing junction resistance and noise contribution. This value is validated across the full operating temperature range and aligns with the 1 mA design example in the LM13700MX datasheet Figure 20.

Can LM13700MX operate from a single 12 V supply?

Yes, LM13700MX supports single-supply operation from 9.5 V to 32 V, as confirmed in Section 6.2 Recommended Operating Conditions. At 12 V, the device delivers usable output swing (±5 V typical buffered), though dynamic range is reduced versus ±15 V operation. Input common-mode range shifts to 0 V to 10.5 V, and peak output voltage drops to approximately ±5.5 V. Designers must verify that IABC and ID bias networks comply with the adjusted headroom - e.g., using 10 kΩ for ID at 12 V yields ~1.2 mA, remaining within specification.

How does LM13700MX differ from LM13600 in buffer behavior?

LM13700MX buffer input bias currents - and thus their DC output levels - are independent of IABC, whereas LM13600 buffer bias current scales directly with IABC. This architectural difference means LM13700MX maintains stable DC operating points during gain modulation, critical for AC-coupled audio VCAs. In contrast, LM13600 exhibits output DC shift with IABC changes, requiring additional servo circuitry. The LM13700MX datasheet explicitly states this distinction in Section 1 "Description" and validates it in electrical characteristics tables.

What is the minimum differential input voltage needed to achieve 0.3 dB gm tracking in LM13700MX?

LM13700MX achieves 0.3 dB gm tracking across both channels without requiring any minimum differential input voltage - the specification reflects inherent matching of the transconductance cells under identical IABC and temperature conditions. Tracking is measured with small-signal inputs (e.g., 10 mVpp) and holds across the full 5–500 μA IABC range and 0°C–70°C ambient. No input signal is needed to validate tracking; it is a DC parameter verified during wafer sort and final test per TI's LM13700MX production data.

Does LM13700MX include ESD protection diodes on all pins?

Yes, LM13700MX incorporates internal ESD protection diodes on all pins, rated per HBM (Human Body Model) at ±2 kV - as documented in the "ESD Ratings" table added in Revision F (November 2015) of the official SNOSBW2F datasheet. These diodes clamp transient voltages to V+ and V− rails and are designed to survive standard handling and board assembly events. External series resistors (>100 Ω) are still recommended on high-impedance nodes like IABC and ID inputs when exposed to connectors or cables.